1. DO NOW
Pick up notes sheet.
Get out half sheet review.

2. LOOKING BACK…. How do Earthquake tell us about Earth’s layers?
Remembering that the outer core is molten metal:
What do “S” waves do in liquids?
What do “P” waves do in liquids?

3. Composition of Earth’s Crust
SES2b. Explain how the composition of the Earth’s crust, mantle and core is determined.

4. ELEMENTS IN EARTH’S CRUST
Earth’s Crust is made up of:
47% Oxygen
28% Silicon
8% Aluminum
5% Iron
4% Calcium
3% Sodium
2% Potassium
2% Magnesium
1% Other

5. WHAT ARE MINERALS? Minerals are the building blocks of rocks
Naturally occurring,
Inorganic,
Solid chemical compound,
Orderly internal structure - crystalline (Atoms arranged in a regular, repeating pattern),
Consistent chemical composition – homogenous.

6. WHAT IS AND IS NOT A MINERAL:
Four Criteria for Minerals
Coal
Brass
Obsidian
Basalt
Fluorite
Inorganic No
Yes
Occurs naturally
Crystalline solid
Consistent chemical composition

7. MINERAL GROUPS Grouped according to chemical composition Silicates
Nonsilicates

8. SILICATES Has BOTH Silicon and Oxygen. Make up 96% of Earth’s crust.
Crystalline Structure:
Silicon-Oxygen Tetrahedron
4 oxygen atoms in pyramid with one silicon atom in the center
Quartz = SiO2
May contain other elements:
Olivine (Mg,Fe)2SiO4
Orthoclase KAlSi3O8
Muscovite KAl3Si3O10(OH)2

9. NONSILICATES Group Description Example Carbonates
Contain carbonate group (CO3)
Dolomite (CaMgCO3)2
Calcite (CaCO3)
Halides
Contain chlorine or fluorine with potassium, sodium or calcium (salts)
Halite (NaCl)
Fluorite (CaF2)
Native elements
Pure elements
Silver (Ag)
Copper (Cu)
Oxides
Contain oxygen AND an element other than silicon
Corundum (Al2O3)
Hematite (Fe2O3)
Sulfates
Contain a sulfate group (SO4)
Gypsum (CaSO4)
Anhydrite (CaSO4)
Sulfides
Contain one or more elements combined with sulfur
Galena (PbS)
Pyrite (FeS2)

10. NONSILICATES
Do NOT contain BOTH silicon AND oxygen (they can have one, the other or neither).
4% of Earth’s crust.
Crystalline structure: no silicon-oxygen tetrahedron.
Crystalline structure includes:
Cubes
Hexagonal prisms
Irregular masses
Structure determines characteristics
Native elements – closely packed, dense

11. IDENTIFYING MINERALS Examine the mineral collections.
How are minerals alike? Different?
What characteristics can be used to classify and identify minerals?

12. PROPERTIES OF MINERALS
Each mineral’s properties are a result of its unique chemical composition and crystalline structure.
Tests used to identify minerals include:
Color
Streak
Luster
Cleavage and Fracture
Hardness
Crystal Shape
Density
Special Properties

13. COLOR Easy to observe. Not reliable.
Some have distinct colors, others are similar in color.
Some minerals come in different colors.
Weathering can conceal true color.

14. STREAK
Color left behind when rubbed on streak plate (unglazed ceramic tile).
Streak color may not match mineral color.
Metallic minerals – dark streak.

15. LUSTER The way a mineral reflects light. How shiny it is.
Types includes:
Metallic
Vitreous (glassy)
Dull

16. CLEAVAGE AND FRACTURE
Cleavage: tendency to split along specific planes to form smooth, flat surface.
Fracture: break unevenly
Irregular or uneven
Splintery or fibrous
Conchoidal or curved

17. HARDNESS Ability to resist scratching.
Based on strength of chemical bonds.

18. CRYSTAL SHAPE Chemistry determines shape.
To form a crystal shape minerals need specific conditions:
Lots of time (they form slowly).
Room to “grow”.
Shapes defined by number and direction of axes.

19. DENSITY Depends on type and arrangement of atoms.
Specific gravity is similar to density – but has no units.

20. SPECIAL PROPERTIES
Fluorescence – ability to glow under UV light – fluorite.
Phosphorescence – continue to glow after UV light off – eucryptite.
Chatoyancy – “cat’s-eye effect – silky appearance – Tiger’s Eye.
Asterism – reflects six- sided star shape – star sapphire.

21. MORE SPECIAL PROPERTIES
Double Refraction – bending light – produces double image – calcite.
Magnetism – magnetic – lodestone .
Radioactivity – unstable atomic nuclei – radium.

22. LAB: MINERAL IDENTIFICATION
Mineral Identification Lab
Consider Color, Streak, Luster, Cleavage or Fracture, Hardness and other properties.
Draw mineral.
Identify using chart.

23. Something to think about:
Which mineral was the hardest to identify? Why?
Which mineral was the easiest to identify? Why?
Which physical property was the most useful in identifying your minerals? Why?
Which physical property was the least useful in identifying your minerals? Why?